1. Field of Invention
The present invention relates to a method of mechanically releasing a parking state in a vehicle equipped with a shift-by-wire shifting device, and more particularly, to a control method of preventing a parking state from being released by inappropriate operation of a parking release apparatus.
2. Description of Related Art
Shift by wire shifting devices are devices that control a transmission, using electric signals, in response to signals generated when a driver operates the shift lever, without transmitting the operational force of the shift lever applied by the user through a mechanical cable, as in the related art.
Meanwhile, double parking or parallel parking is frequently unavoidable due to insufficient parking space in Korea, and accordingly, it is required to park in the N-stage state such that vehicles can be pushed by external force.
Further, it is required to release the parking state such that the vehicle wheels can freely rotate, when washing the vehicle with a car washing apparatus.
Further, it is required to manually shift between the P-stage state and the N-stage state in the vehicles equipped with the shift-by-wire shifting device, as described above, when a problem occurs in the electric system, such as discharge, which is prescribed by law.
Accordingly, as shown in FIG. 1, a parking release apparatus that allows for switching a transmission from a P-stage state to an N-stage state, using a mechanical mechanism is required.
The device shown in FIG. 1 is parking release apparatus where the control method of the present invention can be applied, which includes a motor 502 that is controlled by a controller 500, a first worm wheel 506 that is engaged with a first worm gear 504 provided on a rotary shaft of motor 502 to rotate, a second worm wheel 510 that is engaged with a second worm gear 508 integrally fitted in and/or monolithically formed with first worm wheel 506, and a cable guide 514 that rotates coaxially with second worm wheel 510 and pulls or releases an end of a parking cable 512 while rotating such that operational motion can be transmitted to the transmission.
Further, the parking release apparatus includes a rotation sensor 516 that can sense the amount of rotation of cable guide 514 or second worm wheel 510 and allows controller 500 to control the operational motion transmitted through parking cable 512 by recognizing the amount of rotation of cable guide 514 in response to a signal from rotation sensor 516.
First worm wheel 506 has a tool hole to insert a tool and manually rotate it such that the P-stage state and the N-stage state can be switched when a problem occurs in the electric system, such as discharge, but the tool hole may be used to rotate first worm wheel 506 for fun or a robbery, other than when a problem occurs in the electric system, as described above.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.